U.S. patent number 8,419,828 [Application Number 12/811,793] was granted by the patent office on 2013-04-16 for multi-stage membrane separation process.
This patent grant is currently assigned to Shell Oil Company. The grantee listed for this patent is Zaida Diaz, Henricus Abraham Geers, Arian Nijmeijer, Eric Johannes Puik, Ewout Martijn Van Jarwaarde. Invention is credited to Zaida Diaz, Henricus Abraham Geers, Arian Nijmeijer, Eric Johannes Puik, Ewout Martijn Van Jarwaarde.
United States Patent |
8,419,828 |
Diaz , et al. |
April 16, 2013 |
Multi-stage membrane separation process
Abstract
The invention concerns a process for the removal of gaseous
acidic contaminants, especially carbon dioxide and/or hydrogen
sulphide, in two or more stages from a gaseous hydrocarbonaceous
feedstream (1) comprising hydrocarbons and said acidic
contaminants, using one or more membranes in each separation
stages. The gaseous hydrocarbonaceous feedstream is especially a
natural gas stream. The process is especially suitable for
feedstreams comprising very high amounts of acidic contaminants,
especially carbon dioxide, e.g. more than 25 vol. %, or even more
than 45 vol. %. In a first stage (2) a pure or almost pure stream
of acidic contaminants is separated from the feedstream, the acidic
contaminants (4) stream suitably containing less than 5 vol % of
hydrocarbons. The remaining stream (3) comprises the hydrocarbons
and still a certain amount of gaseous acidic contaminants. In a
second stage (5) a pure or almost pure stream of hydrocarbons (8)
is separated from the remaining stream, where after the then
remaining stream (6) is combined with the feed for the first stage
(1), the hydrocarbon stream suitably containing less than 5 vol %
of acidic contaminants.
Inventors: |
Diaz; Zaida (Katy, TX),
Geers; Henricus Abraham (Rijswijk, NL), Van
Jarwaarde; Ewout Martijn (Amsterdam, NL), Nijmeijer;
Arian (Amsterdam, NL), Puik; Eric Johannes
(Rijswijk, NL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Diaz; Zaida
Geers; Henricus Abraham
Van Jarwaarde; Ewout Martijn
Nijmeijer; Arian
Puik; Eric Johannes |
Katy
Rijswijk
Amsterdam
Amsterdam
Rijswijk |
TX
N/A
N/A
N/A
N/A |
US
NL
NL
NL
NL |
|
|
Assignee: |
Shell Oil Company (Houston,
TX)
|
Family
ID: |
40524968 |
Appl.
No.: |
12/811,793 |
Filed: |
January 7, 2009 |
PCT
Filed: |
January 07, 2009 |
PCT No.: |
PCT/EP2009/050097 |
371(c)(1),(2),(4) Date: |
October 28, 2010 |
PCT
Pub. No.: |
WO2009/087156 |
PCT
Pub. Date: |
July 16, 2009 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20110041687 A1 |
Feb 24, 2011 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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61019669 |
Jan 8, 2008 |
|
|
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Current U.S.
Class: |
95/49; 96/4;
95/43; 95/45; 96/9; 96/7; 95/51 |
Current CPC
Class: |
C10L
3/12 (20130101); C10L 3/102 (20130101); B01D
53/228 (20130101); C10L 3/10 (20130101); B01D
53/225 (20130101); Y02C 10/10 (20130101); B01D
2257/308 (20130101); Y02C 20/40 (20200801); B01D
2317/022 (20130101); B01D 2257/304 (20130101); B01D
2257/306 (20130101); B01D 2257/504 (20130101); B01D
2256/24 (20130101) |
Current International
Class: |
B01D
53/22 (20060101) |
Field of
Search: |
;95/43,45,49,51
;96/4,7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Greene; Jason M
Assistant Examiner: Shumate; Anthony
Parent Case Text
PRIORITY CLAIM
The present application claims priority of U.S. Provisional Patent
Application Ser. No. 61/019,669 filed 8 Jan. 2008.
The present application claims priority from PCT application
PCT/EP2009/050097, published as WO 2009/087156 A1.
Claims
That which is claimed is:
1. A process for the removal of gaseous acidic contaminants from a
gaseous hydrocarbonaceous feedstream comprising such gaseous acidic
contaminants, the process comprising: 1) providing the
hydrocarbonaceous feedstream at a pressure between 30 and 120 bara,
2) contacting the hydrocarbonaceous feedstream with a membrane to
obtain a hydrocarbon rich retentate and an acidic contaminants rich
permeate, 3) contacting the hydrocarbon rich retentate obtained in
step 2) with a second membrane to obtain a hydrocarbon rich
retentate and an acidic contaminants rich permeate, 4) compressing
the acidic contaminants rich permeate obtained in step 3) up till a
pressure between 30 and 120 bara, and 5) mixing the compressed
permeate obtained in step 4) with the feedstream of step 1) further
comprising obtaining the hydrocarbonaceous feedstream from a
gaseous feed comprising hydrocarbons and acidic contaminants by
contacting the gaseous feed with a membrane to obtain the
hydrocarboneous feedstream and an acidic contaminants rich
permeate.
2. The process according to claim 1, in which the feedstream has a
temperature between -20 and 100.degree. C.
3. The process according to claim 1, in which the acidic
contaminants comprise one or more compounds selected from carbon
dioxide and hydrogen sulphide.
4. The process according to claim 3, in which the feedstream
comprises carbon dioxide in an amount between 10 and 95 vol % based
on the total feedstream, and in which the feedstream comprises
hydrogen sulphide in an amount between 0 and 45 vol % based on the
total feedstream.
5. The process according to claim 3, in which the feedstream
comprises hydrocarbons in an amount between 5 and 90 vol % based on
the feedstream.
6. The process according to claim 1, in which the permeate obtained
in step 2) has a pressure between 1 and 30 bara.
7. The process according to claim 1, in which the permeate in step
2) has an acidic contaminants content of >90 vol % based on the
total retentate stream.
8. The process according to claim 1, in which the retentate in step
2) has a hydrocarbons content of between 40 and 80 vol % based on
the total retentate stream.
9. The process according to claim 1, in which the permeate in step
3) has a pressure between 1 and 20 bara.
10. The process according to claim 1, in which the permeate in step
3) has an acidic contaminants content of between 40 and 90 vol %
based on the total retentate stream.
11. The process according to claim 1, in which the retentate in
step 3) has a hydrocarbons content of more than 90 vol %, based on
the retentate.
12. A process for the removal of gaseous acidic contaminants from a
gaseous hydrocarbonaceous feedstream comprising such gaseous acidic
contaminants, the process comprising; 1) providing the
hydrocarbonaceous feedstream at a pressure between 30 and 120 bara,
2) contacting the hydrocarbonaceous feedstream with a membrane to
obtain a hydrocarbon rich retentate and an acidic contaminants rich
permeate, 3) contacting the hydrocarbon rich retentate obtained in
step 2) with a second membrane to obtain a hydrocarbon rich
retentate and an acidic contaminants rich permeate, 4) compressing
the acidic contaminants rich permeate obtained in step 3) up till a
pressure between 30 and 120 bara, and 5) mixing the compressed
permeate obtained in step 4) with the feedstream of step 1) in
which the permeate in step 3) contains less than 10 vol % of acidic
contaminants.
13. The process according to claim 1, comprising a pretreatment of
the hydrocarbonaceous feedstream in order to remove water, the
pretreatment being selected from a glycol treatment, a glycerol
treatment or a molsieve treatment, the process optionally also
comprising removal of C5+ compounds and/or C2-C4 compounds from the
hydrocarbonaceous feedstream.
14. The process according to claim 1, wherein the process
optionally also comprising removal of C5+ compounds and/or C2-C4
compounds from the hydrocarbonaceous feedstream.
15. The process according to claim 12, in which the acidic
contaminants comprise one or more compounds selected from carbon
dioxide and hydrogen sulphide.
16. The process according to claim 15, in which the feedstream
comprises carbon dioxide in an amount between 10 and 95 vol % based
on the total feedstream, and in which the feedstream comprises
hydrogen sulphide in an amount between 0 and 45 vol % based on the
total feedstream.
17. The process according to claim 12, in which the permeate
obtained in step 2) has a pressure between 1 and 30 bara.
18. The process according to claim 12, in which the permeate in
step 2) has an acidic contaminants content of >90 vol % based on
the total retentate stream.
19. The process according to claim 12, in which the permeate in
step 3) has an acidic contaminants content of between 40 and 90
vol% based on the total retentate stream.
20. The process according to claim 12, in which the retentate in
step 3) has a hydrocarbons content of more than 90 vol %, based on
the retentate.
Description
FIELD OF THE INVENTION
The present invention concerns a process for the removal in two or
more stages of gaseous acidic contaminants, especially carbon
dioxide and/or hydrogen sulphide, from a gaseous hydrocarbonaceous
feedstream comprising hydrocarbons and said acidic contaminants,
using one or more membranes in each separation stage.
BACKGROUND OF THE INVENTION
Natural gas is a major energy source. Its importance has increased
in the past decades, and it is expected that its significance will
grow further in next decades. A main concern in the natural gas
production is the presence of acidic contaminants. Many natural gas
fields are known that contain a few percents of acidic
contaminants, and many gas fields are known to comprise large
amounts of acidic contaminants, up till 50 vol % or even more. In
general, the presence of several volume percents of carbon dioxide
and/or hydrogen sulphide is acceptable, as conventional
technologies are known to remove such amounts of acidic
contaminants from the hydrocarbon fraction. Suitable conventional
techniques are the absorption of acidic contaminants with aqueous
amine solutions or with cold methanol, including the regeneration
of the absorption liquids. The removal of higher amounts of acidic
contaminants from natural gas, e.g. 10 vol percents or more, would
result in very large removal units, including many stages,
requiring very high investment and operational costs.
Thus, there is a need for new techniques for the easy and quick
removal of acidic contaminants from natural gas streams containing
high mounts of these compounds. In the past, the use of membranes
has been considered for the removal of the acidic contaminants.
However, up till now no process has be developed for the quick and
easy removal of acidic contaminants from natural gas streams
containing high mounts of these compounds.
SUMMARY OF THE INVENTION
The present invention, now, describes a integrated multistage
process for the removal of acidic contaminants from natural gas
using two or more membranes stages, the membranes having a (much)
higher permeance for the acidic components than for hydrocarbons,
especially methane. In a first stage a relative pure acidic
contaminants stream is obtained by removing all or almost all of
the hydrocarbons from the natural gas stream. The hydrocarbons
containing stream, however, will contain a considerable amount of
acidic contaminants. In a second step, a pure or almost pure
hydrocarbons stream is extracted from the hydrocarbons containing
stream obtained in the first stage. The remaining stream from the
second stage, containing hydrocarbons as well as acidic
contaminants, is recycled to the natural gas feed stream that is
used for the first stage.
In the above way, two streams are obtained, one stream a clean or
almost clean acidic contaminants containing stream, the other
stream a clean or almost clean natural gas stream (or hydrocarbon
stream). The first stream may be used for instance for the
production of sulphur or sulphur compounds, or may be used in an
enhanced oil recovery (EOR) process. The second stream, optionally
after further purification using conventional means, is suitably
used as pipeline gas, or is used for the production of LNG or
synthesis gas, for instance to be used as feedstream for the
production of hydrogen, hydrocarbons (Fischer-Tropsch), methanol,
urea etc.
Thus, the present invention concerns a process for the removal of
gaseous acidic contaminants from a gaseous hydrocarbonaceous
feedstream comprising such gaseous acidic contaminants, the process
comprising: 1) providing the hydrocarbonaceous feedstream at a
pressure between 30 and 120 bara, 2) contacting the
hydrocarbonaceous feedstream with a membrane to obtain a
hydrocarbon rich retentate and an acidic contaminants rich
permeate, 3) contacting the hydrocarbon rich retentate obtained in
step 2) with a second membrane to obtain a hydrocarbon rich
retentate and an acidic contaminants rich permeate, 4) compressing
the acidic contaminants rich permeate obtained in step 3) up till a
pressure between 30 and 120 bara, and 5) mixing the compressed
permeate obtained in step 4) with the feedstream of step 1).
The gaseous hydrocarbonaceous feedstream is especially a natural
gas stream. The process is especially suitable for feedstreams
comprising very high amounts of acidic contaminants, especially
carbon dioxide, e.g. more than 25 vol. %, or even more than 45 vol.
%. In a first stage a pure or almost pure stream of acidic
contaminants is separated from the feedstream, the acidic
contaminants stream suitably containing less than 5 vol % of
hydrocarbons. The remaining stream comprises the hydrocarbons and
still a certain amount of gaseous acidic contaminants. In a second
stage a pure or almost pure stream of hydrocarbons is separated
from the remaining stream, where after the then remaining stream is
combined with the feed for the first stage, the hydrocarbon stream
suitably containing less than 5 vol % of acidic contaminants.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a membrane system for processing a gas stream.
FIG. 2 shows a membrane system for processing a gas stream.
DETAILED DESCRIPTION
The process of the invention separates acidic contaminants
containing hydrocarbons streams, especially natural gas stream,
into two relatively pure streams, an acidic contaminants containing
stream and a hydrocarbon stream. The process uses relatively cheap
membranes. Membrane units, when compared with conventional treating
processes as amine absorption including regeneration, require a
relatively small operational area, require small amounts of energy,
and require only little operational efforts. Also maintenance and
inspection requirements are moderate.
The feedstream for the process of the invention will have a
pressure between 30 and 150 bara. Especially, the feedstream has a
pressure between 40 and 100 bara, preferably between 50 and 90
bara. The feedstream suitably has a temperature between -30 and
120.degree. C., suitably between -20 and 100.degree. C., preferably
between 0 and 50.degree. C.
The acidic contaminants in the feedstream are especially carbon
dioxide and hydrogen sulphide, although also carbonyl sulphide
(COS), carbon disulphide (CS2), mercaptans, sulphides and aromatic
sulphur compounds may be present. Beside acidic contaminants, also
inerts may be present, for instance nitrogen and noble gases as
argon and helium, usually in an amount up till 20 vol %, especially
up till 10 vol %.
The amount of acidic contaminants in the gaseous hydrocarbonaceous
feedstream may vary within a broad range. Suitably, the amount of
carbon dioxide is between 10 and 95 vol % based on the total
feedstream, preferably between 15 and 75 vol %, e.g. for gaseous
hydrocarbonaceous feedstream from subsurface reservoirs, or between
80 and 95 vol %, e.g. from specific recycle streams, especially EOR
recycle streams. The amount of hydrogen sulphide is suitably
between 0 and 45 vol % based on the total feedstream, preferably
between 5 and 40 vol %.
The amount of hydrocarbons in the gaseous hydrocarbonaceous
feedstream may vary within a broad range. Suitably, the feedstream
comprises hydrocarbons in an amount between 5 and 90 vol % based on
total feedstream, preferably between 5 and 15 vol %, e.g. for
recycle streams as EOR recycle stream, or between 20 and 90 vol %,
for instance for feedstreams produced from subsurface natural gas
reservoirs. The hydrocarbons in the feedstream usually will contain
large amounts of methane, suitably between 50 and 98 vol %,
especially 60 and 95 vol %, based on the volume of the total
feedstream.
Membranes to be used in the process of the present invention are
known in the literature. It is advantageous to use membranes with a
high selectivity for acidic contaminants as carbon dioxide and
hydrogen sulphide. The selectivity is defined as the ratio of the
acidic contaminants permeability over the permeability of the
hydrocarbons as measured in single gas experiments. Preferably, the
selectivity of the membrane in step 2) is between 10 and 200,
preferably between 20 and 150.
The permeance for carbon dioxide or hydrogen sulphide of the
membrane in step 2) is suitably between 10.sup.-10 and 10.sup.-4
mol/m2sPa, preferably the carbon dioxide or hydrogen sulphide
permeance through the membrane in step 2) is between 10.sup.-9 and
10.sup.-5 mol/m2sPa.
The permeate obtained in step 2) suitably has a pressure between 1
and 30 bara, preferably between 5 and 25 bara. The retentate
obtained in step 2) will have a pressure more or less the same as
the pressure of the gaseous hydrocarbonaceous feedstream. Suitably
the retentate obtained in step 2) has a pressure which is up till
10% less than the pressure of the feedstream, preferably up till 5%
less.
The permeate obtained in step 2 suitably has an acidic contaminants
content of >90 vol % based on the total retentate stream,
preferably more than 95 vol %. It is observed that the person
skilled in the art by variation of e.g. the permeance of the
membrane, the contact area of the membrane and the contact time
with the membrane is able to vary the purity of the permeate
obtained in step 2). Suitably, the permeate in step 2) has an
hydrocarbon content of less than 10 vol % based on the total
retentate, preferably less than 5 vol %.
The retentate stream obtained in step 2) of the process of the
present invention will contain beside the hydrocarbons, also a
relatively large amount of acidic contaminants. This is due to the
fact that removal of all or almost all acidic contaminants, also
will result in a relatively large amount of hydrocarbons to pass
through the membrane. In general it can be said that the more pure
the acidic contaminants containing stream will be, the more acidic
contaminants will be present in the permeate. Suitably, the
retentate in step 2) has a hydrocarbons content of between 25 and
90 vol % based on the total permeate stream, preferably between 40
and 80 vol %.
The membrane to be used in step 2) of the process of the present
invention may be any membrane known in the art, provided that it
will have a clear selectivity for acidic contaminants. Suitably the
membrane is chosen from a polyethylene oxide based membrane,
preferably a polyethylene oxide based membrane comprising
block-copolymers, especially PEO 600/5000 T6T6T or a cross linked
PEO, a polyimide or polyaramide based membrane, a cellulose acetate
based membrane, a zeolite based membrane, preferably a
silica-alumina phosphate based membrane, especially, SAPO-34, a
micro-porous silica membrane or a carbon molecular sieves
membrane.
The membrane in step 3) may be the same membrane as used in step
2). Suitably the selectivity of the membrane in step 3) is between
10 and 200, preferably between 20 and 150.
The permeance for carbon dioxide or hydrogen sulphide of the
membrane in step 3) is suitably between 10.sup.-10 and 10.sup.-4
mol/m2sPa, preferably the carbon dioxide or hydrogen sulphide
permeance through the membrane in step 2) is between 10.sup.-9 and
10.sup.-5 mol/m2sPa.
The permeate obtained in step 3) suitably has a pressure between 1
and 20 bara, preferably between 5 and 10 bara. The retentate
obtained in step 3) will have a pressure more or less the same as
the pressure of the feedstream. Suitably the retentate obtained in
step 3) has a pressure that is up till 5% less than the pressure of
the feedstream, preferably up till 2% less.
The retentate obtained in step 3) suitably has a hydrocarbons
content of more than 90 vol % based on total retentate stream,
preferably more than 95 vol %, more preferably more than 98 vol %.
Preferably the retentate in step 3) contains less than 5 vol % of
acidic contaminants, preferably less than 2 vol %. It is observed
that the person skilled in the art by e.g. variation of e.g. the
permeance of the membrane, the contact area of the membrane and the
contact time with the membrane is able to vary the purity of the
permeate obtained in step 3). Suitably the permeate in step 3) has
an acidic contaminant content of between 40 and 90 vol % based on
the total permeate stream, preferably between 50 and 80 vol %. The
permeate stream in step 3) is pressurized up till a pressure
between 30 and 150 bar, especially between 40 and 100 bar. Suitably
the pressure is the same pressure as the feedstream pressure.
The membrane to be used in step 3) of the process of the present
invention may be any membrane known in the art, provided that it
will have a clear selectivity for acidic contaminants. Suitably the
membrane is chosen from the same membrane categories as defined
above for step 2).
In a preferred embodiment the process of the present invention
comprises obtaining the gaseous hydrocarbonaceous feedstream from a
gaseous feed comprising hydrocarbons and acidic contaminants by
contacting the gaseous feed with a membrane to obtain the
feedstream and an acidic contaminants rich permeate. In this way
the process of the present invention is preceded by a bulk
separation of hydrocarbons. The acidic contaminants are especially
one or more compounds selected from carbon dioxide and hydrogen
sulphide. By choosing the conditions in an optimum way, a retentate
will be obtained containing high or very high amounts of
hydrocarbons. Suitably, the retentate has a hydrocarbon content of
more than 90 vol %, preferably more than 95 vol %. The membrane to
be used in this additional step may be any membrane known in the
prior art, provided that it will have a clear selectivity for
acidic contaminants, e.g. a selectivity of 5 or higher. Suitably
the membrane is chosen from the same membrane categories as defined
above for step 2). In the additional step the permeate suitably has
a pressure between 1 and 30 bara, preferably between 5 and 15 bara.
The permeate is suitably in a further step pressurized to the
original pressure, preferably together with the permeate of step
3). The selectivity of the membrane in the additional step is
suitably between 10 and 200, preferably between 20 and 150.
The permeance for carbon dioxide or hydrogen sulphide of the
membrane in the additional step is suitably between 10.sup.-10 and
10.sup.-4 mol/m2sPa, preferably the carbon dioxide or hydrogen
sulphide permeance through the membrane in step 2) is between
10.sup.-9 and 10.sup.-5 mol/m2sPa.
The feed for the additional step suitably has a pressure between 30
and 120 bara. Especially, the feed has a pressure between 40 and
100 bara, preferably between 50 and 90 bara. The feed suitably has
a temperature between -30 and 120.degree. C., suitably between -20
and 100.degree. C., preferably between 0 and 50.degree. C. The
retentate in this step will have a pressure more or less the same
as the pressure of the gaseous feed. Suitably the feed has a
pressure up till 5% less than the pressure of the feedstream,
preferably up till 2% less. The retentate suitably contains less
than 10 vol % of acidic contaminants, preferably contains less than
5 vol % acidic contaminants, more preferably less than 2 vol %.
Preferably the hydrocarbons obtained in the pre-separation step are
combined with the hydrocarbons obtained in step 3).
The carbon dioxide and/or hydrogen sulphide rich permeate obtained
in step 2) of the process of the invention may be used for instance
for enhanced oil recovery. In that case the permeate of step 2) is
suitably recompressed up till a pressure suitably between 80 and
400 bara, especially between 150 and 300 bara.
The invention further relates to the use of the compressed carbon
dioxide and hydrogen sulphide rich permeates produced in one or
more processes of the invention in enhanced oil recovery.
The invention also relates to the use of the hydrocarbon rich
retentate produced in one or more processes of the invention as
pipeline gas, LNG feed or GTL feed.
A preferred embodiment of the process of the present invention
comprises a pretreatment of the gaseous carbonaceous feedstream or
the gaseous feed in order to remove water. This is suitably done by
a glycol treatment, for instance using MEG, DEG and/or TEG, a
glycerol treatment or a molsieve treatment. Further, the process
may also comprise the removal of hydrocarbons higher than methane,
preferably at least the C5+ fraction, more preferably also the
C2-C4 fraction, before the carbon dioxide and/or the hydrogen
sulphide is removed.
The invention is described in a non-limiting manner in FIGS. 1 and
2.
In FIG. 1 a dried, gaseous hydrocarbonaceous feedstock 1 (pressure
100 bar, temperature 20.degree. C., 55 vol % CO2) is contacted with
a membrane in unit 2. An almost pure stream of carbon dioxide
(pressure 20 bar, 4 vol % hydrocarbons) is removed from the unit
via line 4. The retentate stream 3, containing a mixture of
hydrocarbons and carbon dioxide, is contacted with a second
membrane in unit 5. An almost pure stream of hydrocarbons (pressure
95 bar, 2 vol % carbon dioxide) is removed via line 8. A permeate
(pressure 20 bar) is removed via line 6 and pressurized in unit 7
and via line 9 combined with feedstock 1.
In FIG. 2 a dried, gaseous hydrocarbonaceous feedstream comprising
carbon dioxide (15 vol %) and hydrogen sulphide (10 vol %) is
contacted with membrane unit 11 to remove a pure stream of
hydrocarbons (1 vol % of carbon dioxide, 1 vol % of hydrogen
sulphide) via line 13. The retentate 12 is pressurized in unit 7
and the compressed feed is treated in the same way as has been
described in FIG. 1. The pure hydrocarbon stream 8 is combined with
stream 13. The retentate stream 6 is combined with stream 12 before
pressurization. Optionally stream 12 may be pressurized in a
separate unit, followed by combination of the pressurized stream 6
and 12.
* * * * *